Movable barrier operators of various kinds are known in the art. Such operators typically serve to effect the selective and controlled movement of a corresponding movable barrier. Various kinds of movable barriers are known, including but not limited to single panel and segmented garage doors, horizontally or vertically pivoting or sliding doors or gates, cross arms, rolling shutters and the like. In general, such movable barriers are selectively moved as between two primary positions (usually a fully opened position and a fully closed position).
For various reasons an obstacle can become positioned in the pathway of such a movable barrier. For example, the rear-end of a vehicle that has not been completely disposed within a garage can extend into the path of travel of a garage door. Automated movement of a garage door under such circumstances can lead to damage of both the vehicle and the garage door and/or the movable barrier operator mechanism itself. As another example, a child or pet may move into the path of a closing movable barrier and risk injury.
Modern movable barrier operators typically make use of one or more techniques to facilitate automated detection of such obstacles. Common techniques include the use of an infrared beam disposed to likely detect the presence, when the beam is broken, of an obstacle in the pathway of the movable barrier. At least one difficulty associated with this technique is a requirement of having an emitter and detector on opposing sides of the movable barrier. This requires both mounting facilities for both sides of the movable barrier and the routing of wires to both sides of the barrier. Another technique proposes the use of a pressure sensitive surface disposed along a leading edge of the movable barrier itself to facilitate detection of an obstacle through contact with that obstacle. This technique requires that the object being protected be impacted for the protection can occur. Therefore with this technique presents a possibility that the protection only limits the damage and does not eliminate it.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will also be understood that the terms and expressions used herein have the ordinary meaning as is usually accorded to such terms and expressions by those skilled in the corresponding respective areas of inquiry and study except where other specific meanings have otherwise been set forth herein.